Field of the Invention
This invention relates to the use of polyesters for modifying hydrophobic surfaces, especially in paper- and boardmaking processes, especially in processes for recycling paper and board, and also in the textile, pulp and printing industries.
Description of Related Art
Energy requirements of manufacturing recycled-content paper are distinctly lower (about two-thirds lower) than for making new paper from wood (virgin-fiber paper), water requirements are only 15%, and water pollution is only about 5%. So it is environmentally beneficial to recycle paper.
Adhesives from self-adhesive labels, hotmelts, tacky coating constituents on recycled coated papers and cartons, etc., are an immense problem in the recycling process because they cannot be completely screened out despite ever greater deployment of mechanical cleaning resources. They constitute a key cause of what are known in the trade as “stickies” and “white pitch”, the hydrophobic properties of which are responsible for their frequent deposition on hot and moving parts and in the wires and felts of papermaking machines and so they may lead to broken paper webs.
Products useful as passivating agents for treating adhesive contaminants such as stickies have been available for years. These dissolved products are said to render the surface of the tacky contaminants more hydrophilic and hence keep them more wettable, thereby reducing their affinity for hydrophobic surfaces, for example wires, felts and rolls.
Similarly, in the production of paper from wood and cellulose, there are organic components such as, for example, resinous fractions known as “pitch” which cause disruptive deposits during the process and lead to quality detriments on the part of the products.
WO 2011015297 discloses reducing the tackiness of stickies with a polymer dispersion comprising copolymers of (meth)acrylic acid.
Numerous documents describe polyesters as good dispersants which additionally modify the surface of materials and inhibit attachment of particles.
Polyesters formed from aromatic dicarboxylic acids, such as terephthalic acid or isophthalic acid, and diols, such as alkylene glycol, are well-known and have in particular been described for use as soil release polymers (SRPs) in laundry detergent and cleaning compositions.
DE-A-10 2007 051279 claims washable dye mixtures with nonionic polyesters and advertises their excellent coloring performance, especially in polar compositions, such as laundry detergents and dishwashing agents, coupled with minimal staining of textiles and surfaces.
DE 1 194 363 discloses a method of finishing and antistaticizing fibers or textiles with an aqueous solution of a polymerizable polyester obtained from polyhydric alcohols and polybasic carboxylic acids.
DE 10 2008 023 803 describes additives for laundry detergent and cleaning compositions obtained by polycondensing an aromatic dicarboxylic acid and/or C1-C4-alkyl esters thereof with ethylene glycol, optionally 1,2-propylene glycol, optionally polyethylene glycol having an average molar mass of 200 to 8000 g/mol, optionally C1-C4-alkyl polyalkylene glycol ethers having an average molar mass of 200 to 5000 for the polyalkylene glycol ether and optionally a polyfunctional compound, and advertises for example their solid consistency and hydrolysis stability. Explicitly disclosed polyesters are prepared using, for example, polyethylene glycol 6000 and a mixture of methyl polyethylene glycol 750 and methyl polyethylene glycol 2000.
DE 198 26 356 describes oligoesters obtained by polycondensing dicarboxylic acids or esters, ethylene glycol and/or propylene glycol, polyethylene glycol, a water-soluble addition product of an alkylene oxide onto C1-C24 alcohols and one or more polyols having 3 to 6 hydroxyl groups and used for example as soil release polymers in laundry detergents. Polyesters explicitly disclosed are obtained, for example, from dimethyl terephthalate, ethylene glycol, 1,2-propylene glycol, polyethylene glycol 1500, a mixture of methyl polyethylene glycol 750 and methyl polyethylene glycol 1820 and pentaerythritol.
U.S. Pat. No. 5,415,739 describes a method of reducing the tackiness of paper furnishes contaminated with adhesives, which comprises adding to the furnish a water-soluble terpolymer derived from polyethylene glycol in amounts >80% by weight, based on the terpolymer obtained from the reaction of phthalic acid or ester, a glycol and polyethylene glycol in the presence of antimony trioxide.
However, when these terpolymers described therein are used for detackification in the recycling operation, the result is unsatisfactory. Moreover, Sb2O3 is classed as a possible carcinogen and its use is undesirable.